35.5 - 37.4 F = 2 - 3 C. That is really cold. BRRRR... I would not expose my orchids to anything less than 10 C for any length of time. For a very brief period of time, the 2-3 C temp probably will not damage them, but be careful especially if any are in S/H or have water on them or their medium is moist. We have transported plants to our orchid society meeting in the back of an un-heated but enclosed truck-bed when there was ice and snow on the ground. That is about a 90 minute drive. We have not noticed any ill effects, but the plant were not exposed to direct cold air and we put them in cardboard boxes. I would keep them 10 C or above, personally, but I may be being too cautious. Good luck.

Cheers,
BD